Organopolysiloxane derivatives are proactively compounded as cosmetic composition-use oil solutions for the purpose of reducing stickiness and oiliness of cosmetics. However, polydimethyl siloxanes have structural characteristics that lead to poor compatibility with skin, resulting in a multitude of problems such as insufficient moisturizing.
In order to solve these problems extensive research has been conducted into imparting surface activity and improved feel to a polyorgano-polysiloxane through introducing a polyoxyethylene group and/or a polyglyceryl group into the dimethylpolysiloxane (e.g. Patent Documents 1 and 2). JP-S-61-123635 and the like describe a graft-type polyoxyethylene-modified silicone and JP-S-57-149290 and the like describe a polyglyceryl-modified silicone which are produced by addition reacting a polyether compound having an allyl group on an end thereof with the SiH group of an organohydrogenpolysiloxane via a hydrosilylation reaction. However, generally, because an organohydrogenpolysiloxane with a large degree of polymerization is frequently used as a raw material, the feel derived from the silicone becomes excessively strong and there are cases in which a natural feel cannot be obtained. Furthermore, because the polyorgano-polysiloxane as a raw material is nothing more than the mean structure, unmodified polyorgano-polysiloxane in which the polyoxyethylene group and the polyglyceryl group are not bonded is produced as an unavoidable by-product or remains in the system. As a result, compatibility with compounded cosmetic raw materials is negatively affected, which may lead to heterogeneity of the system, a cloudy visual appearance, and a decline in emulsion stability.
Additionally, JP-H-04-211605 and the like propose an (AB)n-type organopolysiloxane copolymer in which the silicone unit and the polyoxyethylene unit are alternately bonded (Patent Documents 3 to 5). Additionally, JP-H-2005-042097 and the like propose an (AB)n-type organopolysiloxane copolymer in which the silicone unit and the polyglycerine unit are alternately bonded (Patent Document 6). The amount of unreacted polyorgano-polysiloxane can be reduced because these alternating copolymers have repeating units and, moreover, when used as a cosmetic composition component, are an extremely useful cosmetic raw material because they impart superior feel.
However, in many cases alternating copolymers are synthesized via balance reactions and, as a result, the molecular weight of the alternating copolymer tends to increase. This leads to a problem in that the obtained surface activity and compatibility is suppressed, and thus, further improvement is needed. Additionally, for the same reason, there is a need for further improvement in compatibility with compounded cosmetic raw materials.
On the other hand, AB-type or ABA-type organopolysiloxane copolymers have been proposed in which molecular weight is suppressed and only two or three of the silicone units, having a relatively simple molecular design, and the polyether units such as the polyoxyethylene units are bonded. These organopolysiloxane copolymers comprise hydrophobic silicone units and hydrophilic units and, therefore, are suggested to be useful as surfactants and cosmetic raw materials (Patent Documents 7 to 10). However, with these organopolysiloxane copolymers, when the hydrophobic siloxane unit becomes short, while hydrolysis resistance with respect to liquid change improves, the hydrophobicity and water repellency in the molecule of the same copolymer unavoidably decline and, in some cases, properties as a surfactant and emulsion stability become insufficient. On the other hand, while it is possible to two-dimensionally extend the siloxane chain length, and increase the hydrophobicity of the subject portion, there are cases where the feel derived from silicone as the cosmetic raw material strengthens, and a natural feel cannot be obtained. Additionally, in cases when a long chain siloxane portion is included, in addition to the issue related to feel described above, there are cases where compatibility with other cosmetic raw material components is negatively affected. In particular, when a long chain siloxane portion is mixed with an acidic cosmetic raw material, the long chain siloxane portion is prone to degradation. Thus, there is further need for an organopolysiloxane copolymer that is more useful as a surfactant and cosmetic raw material.
Patent Document 1: Japanese Unexamined Patent Application Publication No. S-61-123635A (Publication No. JP-S-63-016414)
Patent Document 2: Japanese Unexamined Patent Application Publication No. S-57-149290A (Publication No. JP-S-62-034039)
Patent Document 3: Japanese Unexamined Patent Application Publication No. H-04-211605A (Patent No. 3061434B)
Patent Document 4: Japanese Unexamined Patent Application Publication No. H-04-234307A (Patent No. 3071222B)
Patent Document 5: Japanese Unexamined Patent Application Publication No. H-05-163436A (Patent No. 3283277B)
Patent Document 6: Japanese Unexamined Patent Application Publication No. 2005-042097A
Patent Document 7: Japanese Unexamined Patent Application Publication No. 2005-344076A
Patent Document 8: Japanese Unexamined Patent Application Publication No. S-62-195389A (Patent No. 2583412B)
Patent Document 9: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2009-511710A
Patent Document 10: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2009-511712A